Process of roasting ores



No. 624,833. Patented May 9, I899.

E. E. LUNGWITZ.

PROCESS OF BDASTING ORES.

(Application filed June 15, 1893;)

(No Model.)

WITNESSES: g pgvEN'flgR 7 ATTORN EYS TNi mums PETERS co, mom-lawn, WASHINGYON. o, c.

' NlTED STATES i PATENT OFFICE.

EMILE. LUNGWITZ, OF PUEBLO, COLORADO.

PROCESS OF ROASTING ORES.

SPECIFICATION forming part of Letters Patent No. 624,833, dated May 9, 1899.

Original application filed December 3, 1892, Serial No. 453,993. Divided and this application filed June 15, 1893. Serial No; 477,714. (No specimens.)

To all whom it may concern: i.

Be it known that I, EMIL E. LUNGWITZ, a citizen of the United States, residing at Pueblo, in the county of Pueblo and State of 0010- rado, have invented certain new and useful Improvements in Processes of Roasting Ores; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as Will enable others skilled in the art. to which it appertains to make and use the same.

My invention relates to a new and useful process of roasting ores; and it has for its main object the mechanical stirring of the particles of the ore during the roasting operation by suddenly lowering the pressure in the fur-' nace while the blast is shut off.

This application is a division of the application filed by me December 3, 1892, Serial No. 453,993.

In the roasting of sulfid ores as at present conducted in a blast or roasting furnace a considerable percentage of the resulting oxids volatilizes and escapes from the furnace at the moment of formation out of the corresponding sulfids. To prevent such dissipation and consequent loss of the oXids, it is only necessary to conduct the operation of roasting undersuch a. pressure and to exert upon the oxids after their formation out of the corresponding sulfids such a pressure as to prevent their volatilization. The pressure exerted Within the furnace will vary according to the character. of the ore used, but in all cases will equal three atmospheres or over.

In the accompanying drawingis shown a central verticalsection of a blast-furnace,illustrating one means for carrying my invention into effect.

A represents the steel or similar casing of the stack supporting and inclosing the firebrick B. The throat of the furnace is closed by a cap or plate 0, having an opening controlled by a trap-door O, hinged to the under side of the cap. This opening is preferably centrally located, but may be placed toward the side of the throat, if desired. The usual hopper D for feeding ore and fuel is inserted in the throat of the furnace. The dischargeopening in this hopper is controlled by a trapdoor D, hinged to the under side of the hopand air tight chamber in which water is kept circulating to cool the casing A, and to prevent injury to said casing if it should become exposed to the pressure within the furnace through fusing of the fire-brick at any point the water in said chamber is kept under pressure equal to the pressure withinthe furnace. Water is supplied to this cooling-chamber through the nozzles g of the pipes G, leading from the bustle-pipe G ,by any suitable pump, the water entering preferably near the throat of the furnace and descending to the hearth, thus cooling the upper portion of the stack first and being heated gradually as it approaches the hearth, where it escapes through a suitable discharge-pipe G. This hot water may be utilized by feeding it directly to the boiler connected with the engine supplying the blast for the furnace. Suitable pressuregages H and H are applied to the furnace to indicate the pressure exerted within the furnace and the cooling-chamber, respectively, in order that said pressure may be kept equal. Safety-valves I and I may also be applied to the furnace and the cooling-chamber, respectively, to balance the pressures by removing any excess in either. valve I is preferably located just below the trap-door D, and through it the Waste gases and ore is introduced into the furnace, after which the throat of the furnace is sealed. After the fires are started the blast is turned onthrough the twyers and the pressure within the furnace is raised until it exceedsthe pressure at which the resulting oxids volatilize at the temperature necessary for the operation. Dissipation of the oxids is thus pr The furnace safety vented, as the pressure exerted upon the charge is so high that the oXids when formed cannotvolatilize and be carried off through the furnace-throat or over into the flue-dust chamber. Thus by maintaining the required pressure constant throughout the furnace the formation of flue-dust is almost entirely pre vented. Another advantage resulting from the roasting of sulfid ores under pressure is that the roasting of the ores is effected within a much shorter time than in the ordinary process. The active part of the blast for the purpose of roasting is the oxygen contained in the compressed air introduced through the twyers, and as the volume of any gas is in.-

versely proportional to its pressure it follows that as the pressure within the furnace increases the amount of air, and consequently of oxygen, introduced into the furnace will also increase. For example, a cubic foot of the blastintroduced into the furnace under a pressure of four atmospheres contains four times as much air, and hence four times as much oxygen, as a cubic foot of the blast introduced into the furnace ata pressure of one atmosphere. Consequently, other things being equal, the sulfids of the ore being roasted have four times the opportunity to combine with the oxygen in the blast under a pressure of four atmospheres that they have under a pressure of one atmosphere, so that the roastdisturbance of the body of the ore substantially similar to the stirring operation now in use, caused by the compressed gases within the ore mass breaking it open.

My process is applicable not only to the roasting of ores containing a single metallic element, but to ores containing several such elements. The pressure of the blast would of course depend upon the oxid to be obtained from the ore, and where several metallic oxids are formed simultaneously within the furnace the pressure would be sufliciently high to prevent volatilization of the most highly volatile oxid.

In carrying out my process I prefer to em ploy a furnace substantially similar to that shown; but any form of furnace in which the necessary pressure can be maintained may be used. During the roasting operation the mass of ore agglutinates more or less, if it is not constantly stirred. Being under pres sure, the mass breaks up, fissures open, when this pressure is suddenly released. Thus the beneficial effects of stirring are obtained in a novel manner and without the use of mechanical stirrers per 56.

An apparatus capable of practicing the above-described process is fully set forth and disclosed in my United States Letters Patent 'No. 538,785, dated May 7, 1895.

I claim In the roasting of sulfid ores, the method of stirring said ores which consists in effecting the roasting under superatinospheric pressure and suddenly removing the external pressure on the ore while the blast is tempo- EMIL E. LUNGVVITZ.

Vitnesses:

HUGO SCHWEITZER, BERNHARD REMMERs. 

